Estudo da ordem supramolecular em sistemas de misturas de ácidos fosfônicos de uma e duas cabeças

Abstract

Self-assembled molecules exhibit key functionalities for the development of novel technologies and applications. Usually, molecular systems that exhibit long-range positional order are employed in their pure form. In this work we observe that a combination of an amphiphilic molecule, Tetradecyl-phosphonic Acid (TPA), and a diphosphonate molecule with similar length, 1,10-decyldiphosphonic acid (DdPA) induces distinct long-range ordered structures depending on the relative volume of dilutions used for drop coating on Si substrates with native SiO2 layer. Besides phase segregation observed for systems with large DdPA relative amount we were able to identify volume-dominant periodic molecular structures for mixtures with larger TPA relative volumes that consist of 3 and 5 molecules of TPA and DdPA arranged in specific symmetries, retrieved by synchrotron X-ray diffraction. Atomic Force Microscopy measurements indicate that, despite such bulk ordered supramolecular mixing, exceeding TPA molecules cap ordered domains, encapsulating the DdPA:TPA mixed layers into a single-component surface termination.